The Animal Vestibular Neurophysiology Core (AVNC) will consist of two separate facilities capable of delivering precise, computer-controlled, vestibular stimulation to awake behaving experimental animals. One facility, for felines and rodents, will house a turntable on a tilt stand, capable of delivering controlled rotations about an earth-vertical axis (EVA), an off-vertical axis tilted 10-20 degrees (OVA), and an earth-horizontal axis (EHA). In the EVA mode, sinusoids and velocity trapezoids provide stimulation to the semicircular canals; constant velocity OVA rotation stimulates the otolith organs. EHA mode can provide controlled pitch and roll stimuli of any desired waveform (typically position trapezoids and sinusoids). The other facility, designed for subhuman primates, consists of a dual-axis turn table that allows a rich variety of vestibular stimuli. Positioning the animal carrier with respect to an inner, earth-horizontal, axis provides roll, pitch, and rotation in the planes of the vertical canals. This axis, in turn, mounts on a superstructure on top of an earth-vertical axis turntable. In addition, the superstructure can be offset from the vertical rotation axis; such eccentric rotation, besides providing a rotatory stimulus, will also provide a linear acceleratory (centripetal) acceleration. This apparatus has additional modes of action that will be detailed below; it is capable of delivering a wide variety of linear and angular accelerations that should permit many types of vestibular stimulation, including selective and combined activation of horizontal semicircular canals, vertical canals, and the otolith organs. The AVNC facility will support the synergistic and collaborative research activities of several existing laboratories whose equipment is currently in heavy use. This Core will allow additional new experiments that go beyond the capabilities of the existing individual laboratories. The AVNC will also provide the ability to conduct new studies and generate new research ideas that can be pursued without disrupting the ongoing research activities of the participating investigators.